What Pharmacists Should Know About Novo Nordisk–Eli Lilly GLP-1 Ad Suit

Patients are already walking into pharmacies asking whether one glucagon-like peptide-1 (GLP-1) medication really beats another, and a new legal fight between the 2 market leaders is about to sharpen those questions. Novo Nordisk has sued Eli Lilly in federal court over Lilly's national advertising, alleging the ads compare the highest doses of tirzepatide (Zepbound, Mounjaro) against lower, older doses of semaglutide (Wegovy, Ozempic) while omitting newer, higher-dose formulations.

For pharmacists, the value of following the dispute is less about who wins in court and more about being ready to restore the clinical context these ads compress, starting with the fact that dose, not just drug, drives the numbers patients see on TV. Here is what to know.^1-4

The Dosing Dispute at the Center of the Case

At issue are different campaigns. The first compares tirzepatide, marketed as Zepbound, at its maximum tolerated 10-mg and 15-mg doses against semaglutide, marketed as Wegovy, at 1.7 mg and 2.4 mg, without mentioning the 7.2-mg injectable Wegovy dose the FDA approved in March 2026.

Novo Nordisk points to its STEP UP trial (NCT05649137), a 72-week study of 1407 adults with obesity in which the 7.2-mg dose produced a mean weight reduction of about 19% (18.8%), roughly 47 pounds, versus 3.9% with placebo. Because no head-to-head trial has compared the highest doses of the medicines, Novo argues the comparison is materially misleading. The second campaign compares tirzepatide, as Mounjaro, at 15 mg against semaglutide, as Ozempic, at 1 mg, omitting the 2-mg maintenance dose approved more than 4 years ago.^1,2

“When a patient comes in citing an ad claiming one GLP-1 is ‘better,’ I walk them through what's actually being compared,” Hana Kahleova, MD, PhD, MBA, director of clinical research at the Physicians Committee for Responsible Medicine, explained to Pharmacy Times.

“A fair comparison between these drugs requires matching doses, or at minimum, comparing each drug's own top approved dose against the other's,” she explained. “When an ad puts a maximum dose of one product against a starting or mid-range dose of the competitor, it's not really telling you which drug works better; it's telling you which doses the advertiser chose to show.”

Kahleova said that, when counseling a patient, she explains that “both drug classes have real, well-documented dose-response curves: higher doses of semaglutide or tirzepatide generally produce more weight loss than lower doses of the same drug, so almost any GLP-1 can be made to look superior or inferior depending on which rung of its own ladder you compare it against.” She noted that what matters most clinically “is comparing top dose to top dose, or matching doses, when that's the real question a patient is asking.”

Lilly Points to Its Head-to-Head Trial

Lilly's comparative messaging draws on SURMOUNT-5 (NCT06047548), the first head-to-head trial of the agents, in which tirzepatide produced a mean weight reduction of about 20.2% versus 13.7% for semaglutide over 72 weeks in 751 adults with obesity or overweight. That trial tested semaglutide at the 1.7-mg and 2.4-mg doses available when it was designed; the same doses Novo now says the ads should no longer feature.

In response to the suit, Lilly said it stands "firmly behind" its advertising, describing it as "truthful," "transparent," and "grounded in the most direct scientific evidence available," and said Novo was asking a court to stop Lilly from communicating trial results rather than compete on the merits.^3-5

The distinction matters clinically: SURMOUNT-5 is a direct comparison, while the 7.2-mg Wegovy figures come from a placebo-controlled trial, not a head-to-head study against tirzepatide. Pharmacists asked to compare the two can note that no trial has yet pitted the highest doses of each against the other.^1,5

Where the Case is Headed

Novo Nordisk sent Lilly a cease-and-desist request before suing and says Lilly declined to pull or meaningfully correct the ads. It is seeking a permanent injunction requiring Lilly to remove the disputed advertising across all platforms and run a corrective campaign and has signaled it will file for a preliminary injunction to block the ads before the case is resolved.

The suit also arrives amid heightened federal scrutiny of GLP-1 promotion: the FDA's Office of Prescription Drug Promotion has sent warning letters to Lilly, Novo Nordisk, and Hims & Hers over marketing materials as part of a broader crackdown on the category.^1,2,6

What This Means at the Pharmacy Counter

The practical takeaway for pharmacists is durable regardless of how the litigation resolves. Direct-to-consumer weight-loss ads compress complex, dose-dependent efficacy data into a single headline number, and patients increasingly arrive with those numbers already in mind.

Pharmacists are well positioned to reframe the conversation: that a percentage of weight loss reflects a specific dose in a specific trial population, that titration and tolerability shape what any individual actually achieves, and that no trial has yet compared the highest doses of the 2 medicines head-to-head. Whichever product a patient is prescribed, the counseling opportunity is the same, restoring the context the ads leave out.^1,2

“Comparing across separate trials rather than a shared study, especially trials that may differ in population, duration, and design, is a well-known way to draw conclusions the data can't actually support,” Kahleova cautioned. “Until a proper head-to-head trial includes the 7.2-mg dose [of semaglutide], I'd tell both patients and prescribers that we're choosing between these 2 options based on individual factors, such as gastrointestinal tolerability, dosing schedule, cost and insurance coverage, and other health conditions, rather than a settled answer on which drug wins at these doses.”

REFERENCES

1. Novo Nordisk takes action to stop multiple misleading national GLP-1 advertising campaigns by Eli Lilly. News Release. Novo Nordisk. Released July 21, 2026. Accessed August 21, 2026. https://www.novonordisk.com/content/nncorp/global/en/news-and-media/news-and-ir-materials/news-details.html?id=916584

2. Novo Nordisk sues Eli Lilly over GLP-1 advertising, alleging misleading dosing comparisons. Pharmaceutical Executive. Published July 21, 2026. Accessed August 21, 2026. https://www.pharmexec.com/view/novo-nordisk-sues-eli-lilly-glp-advertising-alleging-misleading-dosing-comparisons.

3. Constantino AK. Novo Nordisk sues Eli Lilly, alleging misleading GLP-1 advertising. CNBC. Published July 21, 2026. Accessed August 21, 2026. https://www.cnbc.com/2026/07/21/novo-nordisk-sues-eli-lilly-glp-1-ads.html

4. Novo Nordisk says it's suing Eli Lilly, accusing it of false advertising. NBC News. Published July 21, 2026. Accessed August 7, 2026. https://www.nbcnews.com/business/business-news/novo-nordisk-says-suing-eli-lilly-accusing-false-advertising-rcna588513

5. Campbell P. SURMOUNT-5: Tirzepatide bests semaglutide in head-to-head weight loss trial. HCPLive. Published December 4, 2024. Accessed August 7, 2026. https://www.hcplive.com/view/surmount-5-tirzepatide-best-semaglutide-in-head-to-head-weight-loss-trial

6. Ferruggia K. FDA moves to restrict mass-marketed compounded GLP-1 products. Pharmacy Times. Published February 12, 2026. Accessed August 21, 2026. https://www.pharmacytimes.com/view/fda-moves-to-restrict-mass-marketed-compounded-glp-1-products